JP2503642Y2 - Supercharged engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a supercharged engine in which a main turbocharger and a sub-turbocharger are arranged in parallel and the number of turbochargers to be operated is changed according to operating conditions.

[Prior Art] A main turbocharger and a sub-turbocharger are arranged in parallel to the engine body. In the low-speed range, the supercharger operation of the sub-turbocharger is stopped to supercharge only in the main turbocharger. A supercharged engine of a so-called two-stage twin turbo system, which operates a turbocharger, is known (Japanese Patent Laid-Open No. 61-112734, Japanese Patent Application No. 1-112734).
-300873). The structure of this type of supercharged engine is as shown in FIG. 6, for example. Engine body 91
On the other hand, a main turbocharger (T / C-1) 92 and a sub turbocharger (T / C-2) 93 are provided in parallel. The intake and exhaust systems connected to the sub turbocharger 93 are provided with an intake switching valve 94 and an exhaust switching valve 95, respectively.
4. By fully closing both exhaust switching valves 95, only the main turbocharger 92 is supercharged, and by opening both fully, the sub turbocharger 93 is also supercharged. It can be activated.

In such a supercharged engine, the exhaust switching valve
Even when 95 is fully closed, that is, even when supercharging only the main turbocharger before switching to the two turbocharger, as shown in FIG. Due to the pulsation (96) of the exhaust gas, the sub-turbocharger 93 can be made to idle, and the sub-turbocharger can be allowed to rotate in the run-up direction before switching from one turbocharger to two turbochargers.

[Problems to be Solved by the Invention] However, in the engine with a supercharger as described above, the position of the exhaust gas switching valve 95 provided downstream of the turbine of the auxiliary turbocharger has an influence on the engine performance as described below. give.

That is, the farther the exhaust switching valve 95 is from the turbine of the sub turbocharger 93 (the longer the distance 1 is during this time), in other words, the turbine of the sub turbocharger 93 and the exhaust switching valve 95.
The larger the exhaust volume between the two, the greater the exhaust pulsation effect shown in Fig. 7, and the greater the number of spare idle rotations of the secondary turbocharger before switching to the two turbocharger becomes The shock at the time of switching to the turbocharger is reduced and smooth turbocharger switching is possible. However, at the same time, if the exhaust volume is large, the increase in supercharging pressure by the main turbocharger 92 is delayed by that amount, and the supercharging response (acceleration response) is reduced.

On the contrary, the closer the exhaust gas switching valve 95 is to the turbine of the sub turbocharger 93 (the shorter the distance 1 between them), in other words,
As the exhaust volume between the turbine of the sub turbocharger 93 and the exhaust switching valve 95 is smaller, the supercharging response is improved, but the exhaust pulsation effect is reduced, so the spare idling number of the sub turbocharger is reduced accordingly. The shock when switching turbochargers will be large.

FIG. 8 and FIG. 9 show the effects on the engine performance. That is, when l is small, the set supercharging pressure is reached quickly (Fig. 8), but the preliminary idling number of the auxiliary turbocharger is low (Fig. 9). If l is large, the spare idling number of the sub-turbocharger can be increased (9th
(Fig.), The rise of the supercharging pressure is slow and the supercharging response decreases (Fig. 8). Therefore, in the conventional engine with a supercharger, it is difficult to reduce shock at the time of switching the turbocharger by increasing the auxiliary idling speed of the auxiliary turbocharger and improve the supercharging response.

The present invention pays attention to such a problem, and optimally controls the exhaust volume around the turbine of the secondary turbocharger in the two-stage turbo system engine,
The objective is to achieve both shock reduction and turbocharging response improvement when switching turbochargers.

[Means for Solving the Problems] An engine with a supercharger according to the present invention for this purpose includes a main turbocharger and an auxiliary turbocharger provided in parallel with an engine body, and an engine connected to the auxiliary turbocharger. The intake and exhaust systems are equipped with an intake switching valve and an exhaust switching valve that both cause the sub-turbocharger to perform supercharging operation when fully open, and stop supercharging operation of the sub-turbocharger when both are fully closed. In the turbocharged engine, the exhaust switching valve includes a first exhaust switching valve provided on the turbine downstream side of the auxiliary turbocharger,
It is provided upstream of the first exhaust switching valve in the exhaust system of the engine connected to the turbine of the sub-turbocharger, and is closed when the supercharging pressure is lower than a preset pressure. It is characterized by comprising a second exhaust switching valve which is opened when

[Operation] In such a supercharged engine, in the initial stage of acceleration in which the supercharging pressure is lower than the predetermined set pressure, the second exhaust switching valve provided upstream of the first exhaust switching valve is Since it is closed, the exhaust volume around the turbine of the sub-turbocharger is reduced and the supercharging response is improved. When the supercharging pressure reaches a predetermined set pressure, the second exhaust switching valve is opened, so that the exhaust volume becomes large, the exhaust pulsation effect becomes large, and the preliminary idling number of the auxiliary turbocharger is increased. Then, in this state, switching from one turbocharger to two turbochargers is performed, so the sub-turbocharger is run at a sufficiently high rotational speed before switching,
Shock when switching turbochargers is reduced. Therefore, at the time of acceleration, both improvement of the supercharging response and reduction of the turbocharger switching shock are achieved.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

First Embodiment FIG. 1 shows a supercharged engine according to a first embodiment of the present invention, in which the present invention is applied to a 6-cylinder engine.

In FIG. 1, 1 is an engine, 2 is a surge tank,
3 shows an exhaust manifold. The exhaust manifold 3 includes two cylinder groups, # 1 to # 3 cylinder groups and # 4 to # 6 cylinder groups, which do not involve exhaust interference.
And the gathering portions are communicated with each other by the communication passage 3a. Reference numerals 7 and 8 denote a main turbocharger and a sub turbocharger arranged in parallel with each other. Each of the turbines 7a, 8a of the turbochargers 7, 8 is connected to the collecting part of the exhaust manifold 3 and the respective compressor 7
b and 8b are connected to the surge tank 2 via an intercooler 6 and a throttle valve 4. Main turbocharger 7
Is operated from the engine low speed range to the high speed range, and the auxiliary turbocharger 8 is stopped in the engine low speed range.

An exhaust switching valve is provided in the exhaust system connected to the turbine 8a of the auxiliary turbocharger 8 and an intake switching valve is provided downstream of the compressor 8b of the auxiliary turbocharger 8 in order to enable operation and stop of both turbochargers 7 and 8. 18 are provided. When both the intake and exhaust switching valves are fully open, both turbochargers 7 and 8 are operated. This exhaust gas switching valve is a downstream side of the turbine 8a of the sub turbocharger 8, and is provided near the confluence of the main turbocharger 7 with the exhaust pipe from the turbine 7a. Second exhaust switching valve provided immediately after the outlet of the turbine 8a in the exhaust system connected to the turbine 8a of No. 8
It is composed of 17b and. The first exhaust switching valve 17a is opened and closed by the actuator 16, and the second exhaust switching valve 17b is opened.
Is opened and closed by the actuator 34.

In the intake passage of the auxiliary turbocharger 8 that is stopped in the low speed range, an intake bypass passage 13 that connects the upstream side and the downstream side of the compressor 8b is provided in order to facilitate the switching from one turbocharger to two turbochargers. An intake bypass valve 33 is provided in the intake bypass passage 13. The intake bypass valve 33 is opened and closed by the actuator 10. The air flow downstream side of the intake bumper passage may be connected to the intake passage upstream of the compressor of the auxiliary turbocharger 8. Further, the check valve 12 is provided in the bypass passage that connects the upstream side and the downstream side of the intake switching valve 18, and the intake switching valve 18
Even when closed, when the compressor outlet pressure on the side of the auxiliary turbocharger 8 becomes larger than that on the side of the main turbocharger 7, air can flow from the upstream side to the downstream side. In FIG. 1, 14 indicates an intake passage on the compressor outlet side, and 15 indicates an intake passage on the compressor inlet side. The intake passage 15 is connected to the air cleaner 23 via an air flow meter 24. A front pipe 20 forming an exhaust passage is connected to an exhaust muffler 22 via an exhaust gas catalyst 21.

The intake switching valve 18 is opened and closed by the actuator 11. Reference numeral 9 indicates an actuator for opening and closing the waste gate valve 31. In order to turn on and off the boost pressure or load that operates the actuators 10, 11, 16, 34 (selectively switch between boost pressure or negative pressure and atmospheric pressure), first, second, third, Fourth and fifth three-way solenoid valves 25, 26, 27, 28, 32
Is provided. Switching of the three-way solenoid valves 25, 26, 27, 28, 32 is performed according to a command from the engine control computer 29. When the three-way solenoid valve 25 is turned on, the actuator 11 is operated so that the intake switching valve 18 is fully opened, and when it is turned off, the actuator 11 is operated so that the intake switching valve 18 is fully closed. When the three-way solenoid valve 28 is ON, the actuator 16 is operated so that the first exhaust switching valve 17a is fully opened, and when it is OFF, the first exhaust switching valve 17a is fully opened.
Of the actuator 16 so that the exhaust switching valve 17a of
Activate ON of the three-way solenoid valve 32 is the second exhaust switching valve 17
Actuate actuator 34 so that b is fully open, and turn it off.
The actuator 34 so that the exhaust switching valve 17b is fully closed.
Activate 16a is the diaphragm chamber of the actuator 16, 10a is the diaphragm chamber of the actuator 10, and
Reference numerals 1a and 11b denote a diaphragm chamber of the actuator 11, and 34a denotes a diaphragm chamber of the actuator 34.

The engine control computer 29 is electrically connected to various operating condition detection sensors of the engine, and receives signals from the various sensors. The engine operating condition detection sensor includes an intake pipe pressure sensor 30, a throttle opening sensor 5, and an air flow meter 2 as an intake air amount measurement sensor.
4, O ₂ sensor 19 included.

The engine control computer 29 includes a central processor unit (CPU) for calculation, a read-only memory (ROM) that is a read-only memory, a random access memory (RAM) for temporary storage, and an input / output interface (I / D interface). ), It is equipped with an A / D converter that converts analog signals from various sensors into digital quantities. FIG. 2 shows a control program for opening / closing the switching valve, which is stored in the ROM and read by the CPU, and is a program for practically operating the valve opening / closing.

The control in this embodiment will be described with reference to the supercharging pressure characteristic shown in FIG. 3 together with the control flow shown in FIG. In addition, in FIG. 2, the first to fifth three-way solenoid valves are represented as VSV No. 1 to VSV No. 5, respectively.
Further, in FIGS. 2 and 3, the turbocharger is represented by T / C.

First, in FIG. 2, in step 100, the valve control routine is entered, and in step 101, the supercharging pressure is changed to the intake pipe pressure (PM)
Read in. It is determined whether the intake pipe pressure (PM) is higher or lower than a preset pressure, for example, 500 mmHg (step 102), and if it is lower than the set pressure, step 104
At, the fifth three-way solenoid valve 32 is turned off, and the second exhaust switching valve 17b is closed. By fully closing the second exhaust switching valve 17b, the volume of the exhaust system connected to the turbine 8 of the auxiliary turbocharger 8 is kept small, so the boost pressure by the main turbocharger 7 rises quickly during acceleration. , Supercharging response is improved. At this time,
As will be described later, the number of operating turbochargers is one (that is, only the main turbocharger 7 is operating), so the first exhaust switching valve 17a is closed.

When it is determined in step 102 that the intake pipe pressure PM (supercharging pressure) has reached the set pressure, the fifth three-way solenoid valve 32 is turned on in step 103, and the second exhaust switching valve 17b is fully opened. To be done. By fully opening the second exhaust switching valve 17b, the volume of the exhaust system connected to the turbine 8a of the sub turbocharger 8 becomes large, so the exhaust pulsation effect as shown in FIG. 7 becomes large, and the sub turbocharger becomes larger. The preliminary idling speed (running speed) of 8 is increased. The fact that the supercharging pressure has reached the set pressure means that the time (state) at which switching from the one turbocharger to the two turbocharger is approaching, so the second exhaust gas switching valve 17b before the turbocharger switching is performed. By fully opening, the running speed of the auxiliary turbocharger 8 before switching is further increased, and the turbocharger switching is performed more smoothly (shock at the time of switching is reduced).

After controlling the opening / closing of the second exhaust switching valve 17b, the routine proceeds to step 105, where the intake air amount Q of the engine is read. The intake air amount is a signal from the air flow meter 24. Next step 10
At 6 it is determined whether it is in the high speed range or the low speed range, that is, whether it is the two turbocharger operating range or the one turbocharger operating range. In the example shown in the figure, for example, if Q is greater than 5500l / min, it is determined that two turbocharger operation should be switched to
When it is less than min, it is judged as one turbocharger operating range. However, as will be described later, there is a time delay before actually switching to two turbocharger operation, so 6000
It will switch around l / min.

If it is determined in step 106 that the operation should be switched to the two turbocharger operation, the process proceeds to step 107. If the second three-way solenoid valve 26 is ON, it is turned OFF and the intake switching valve 18 is opened (partial). Stop opening). After turning off the second three-way solenoid valve 26, or if it was originally off, proceed to step 108, turn on the third three-way solenoid valve 27,
Intake bypass valve by introducing the intake pipe pressure (supercharging pressure) downstream of the compressor into the diaphragm chamber 10a of the actuator 10.
Close 33. Before the intake bypass valve 33 is closed, the exhaust switching valve 17 is in a fully closed state, but since the engine exhaust pressure is applied to the turbine 8a of the sub turbocharger 8, as described above, the sub turbocharger 8 runs in the auxiliary rotation (preliminary rotation). It has been idle). Then, when the intake bypass valve 33 is closed, the outlet pressure of the compressor 8b is increased, and the running speed is increased.

Next, after the third three-way solenoid valve 27 is turned ON, a predetermined time required for increasing the running speed of the turbocharger on the operation stop side, that is, the sub-turbocharger 8, for example, with a time delay of 1 second, is applied for 1 second. After a lapse of time, in step 109, the fourth three-way solenoid valve 28 is turned on to guide the intake pipe pressure (supercharging pressure) downstream of the compressor to the diaphragm chamber 16a of the actuator 16 to fully open the first exhaust switching valve 17a. If the compressor pressure of the sub turbocharger 8 becomes higher than the compressor pressure of the main turbocharger 7, the supercharged air of the sub turbocharger 8 is supplied to the engine via the check valve 12. Then, after the fourth three-way solenoid valve 28 is turned on, the first three-way solenoid valve 25 is turned on in step 110 after a predetermined time, for example, 0.5 seconds has passed, and the diaphragm chamber of the actuator 11 is turned on.
The intake pipe pressure (supercharging pressure) downstream of the compressor is guided to 11a to fully open the intake switching valve 18. In this state, the two turbochargers are activated (when the two turbochargers are switched to after the predetermined time has passed, the intake air amount is approximately 6000 l / min, which is a target for good turbine efficiency). Then, it proceeds to step 117 and returns.

If it is determined in step 106 that one turbocharger is operating, the process proceeds to step 111, and the first three-way solenoid valve 25 is turned on.
As the FF, the intake switching valve 18 is fully closed, and the fourth step is performed at step 112.
The three-way solenoid valve 28 is turned off to fully open the first exhaust switching valve 17a, and in step 113 the third three-way solenoid valve 27 is turned off to fully open the intake bypass valve 33. Step 114 in this state
Go to and determine whether the load is light or heavy. Although the drawing shows the case where the intake pipe pressure (read in step 101) is taken as an example of the load signal, the throttle opening, intake air amount / engine speed may be substituted instead of the intake pipe pressure. . For example, when the intake pipe pressure PM is less than -100 mmHg, it is determined as a light load, and when it is -100 mmHg or more, it is determined as a high load.

If the load is determined to be high in step 114, step 116
Then, the second three-way solenoid valve 26 is turned off. Since the first and second three-way solenoid valves 25 and 26 are turned off and the atmospheric pressure is introduced to both the diaphragm chambers 11a and 11b of the actuator 11, the intake switching valve 18 is fully closed and the step
Proceed to 117 and return. In this state, the intake switching valve 18 is fully closed, the first exhaust switching valve 17a is fully closed, and the intake bypass valve 33
Since it is fully open, one turbocharger is activated when the intake air amount is small, and the supercharging pressure and torque response are good.

If the load is judged to be light in step 114, step 1
Proceed to 15 and turn on the second three-way solenoid valve 26 to turn on the actuator.
The negative pressure in the surge tank 2 is introduced to the diaphragm 11b of 11 to open the intake switching valve 18. At this time, the intake negative pressure is changed from the second three-way solenoid valve 26 to the diaphragm chamber 11 of the actuator 11.
Introduced into b, the intake switching valve 18 is opened. In this state, since the first exhaust switching valve 17a is closed, the sub turbocharger 8 does not operate, and only the main turbocharger 7 operates. However, since the intake switching valve 18 is open in the intake passage 14, the intake passages for two turbochargers are open. Therefore, air is taken in through the compressors 7b, 8b of both turbochargers. As a result, a large amount of supercharged air can be supplied to the engine 1, and the acceleration characteristic from a low load is improved. Then, it proceeds to step 117 and returns.

In the above control, the supercharging pressure characteristics when operating one turbocharger and when operating two turbochargers are as shown in FIG. However, the effect of opening and closing the second exhaust gas switching valve 17b is not shown in FIG.

In the high speed range, both the intake switching valve 18 and the first exhaust switching valve 17a are opened and the intake bypass valve 33 is closed. As a result, the two turbochargers 7, 8 are supercharged, a sufficient amount of supercharged air is obtained, and the output is improved. At this time, the supercharging pressure is controlled by the waste gate valve 31 so as not to exceed the set pressure.

Both the intake switching valve 18 and the first exhaust switching valve 17a are closed and the intake bypass valve 33 is opened in the low speed range and under high load. As a result, only one turbocharger 7 is driven. The reason why one turbocharger is used in the low rotation speed region is that the one turbocharger supercharging characteristic is superior to the two turbocharger supercharging characteristic in the low rotation speed region as shown in FIG. By using one turbocharger, the boost pressure and the rise of torque are accelerated, and the response is prompt. Also at this time, the supercharging pressure is controlled by the waste gate valve 31 so as not to exceed the set pressure.

In the low speed range and when the load is light, the intake switching valve 18 is opened while the first exhaust switching valve 17a is closed. By this, 1
While the individual turbocharger is still driven, the intake passages for two turbochargers are opened, and the increase in intake resistance in one turbocharger can be eliminated. As a result, the boost pressure rising characteristics and response in the initial stage of acceleration from a low load can be further improved.

When shifting from the low speed region to the high speed region, that is, when switching from one turbocharger operation to two turbocharger operation, the intake bypass valve 33 is closed when the intake air amount Q reaches 5500 l / min, and the sub turbocharger 8 After a time delay (after 1 second has elapsed in the present embodiment) after the increase in the running speed of the engine, the first exhaust gas switching valve 17a is fully opened, and then the intake air switching valve 18 is fully opened, so that two turbochargers are installed. The supercharging operation is started. As described above, before the intake bypass valve 33 is closed, when the boost pressure reaches the set pressure, the second exhaust switching valve 17b is closed. Therefore, at this stage, the preliminary idling speed of the auxiliary turbocharger 8 has already been reached. Is raised,
By closing the intake bypass valve 33 before switching the turbocharger, the running speed of the auxiliary turbocharger 8 is further increased, and the shock at the time of switching the turbocharger is further reduced.

Second Embodiment Next, FIG. 4 shows a second embodiment of the present invention.

In the present embodiment, immediately after the outlet of the turbine 8a of the sub-turbocharger 8, a chamber 41 having a volume that can communicate with the exhaust passage is provided, and the second exhaust switching valve 17b is provided at the inlet of the chamber 41. To be Opening / closing control of the first exhaust gas switching valve 17a and the second exhaust gas switching valve 17b is performed in the same manner as in the first embodiment, and the second exhaust gas switching valve 17b is set at the initial stage of acceleration when the boost pressure does not reach the set pressure. When the exhaust volume is kept small and the boost pressure reaches the set pressure, the second exhaust switching valve 17b is opened, the exhaust volume is expanded and the preliminary idling number of the auxiliary turbocharger 8 is increased. Prepared for switching to individual turbocharger. In this way, the second exhaust switching valve is positively provided with the additional exhaust volume portion.
The exhaust volume may be changed depending on the size of 17b.

Third Embodiment Next, FIG. 5 shows a third embodiment of the present invention.

In the present embodiment, the second exhaust switching valve 17b is provided on the upstream side (inlet side) of the turbine 8a of the auxiliary turbocharger 8. The opening / closing control of each valve is based on the first embodiment.

By opening and closing the second exhaust switching valve 17b on the turbine inlet side in this way, the exhaust volume can be minimized when the valve is closed in the initial stage of acceleration, and a very good supercharging response can be obtained. However, since the turbine inlet side is considerably hotter than the outlet side, it is necessary to use a valve with high heat resistance.

[Advantages of the Invention] As described above, when using the supercharged engine of the present invention, in the engine of the two-stage turbo system, the first and second exhausts are connected to the exhaust system connected to the turbine of the auxiliary turbocharger. A switching valve is provided so that the exhaust volume can be changed and controlled by opening and closing the second exhaust switching valve. Therefore, at the time of low supercharging pressure in the initial stage of acceleration, the second exhaust switching valve is closed to keep the exhaust volume small and supercharge The response can be improved, and when the boost pressure reaches the set pressure, the second exhaust switching valve is opened to increase the exhaust volume, and the exhaust pulsation effect is enhanced to increase the preliminary idling number of the auxiliary turbocharger. It is possible to smoothly switch from the individual turbocharger to the two turbocharger and reduce the shock at the time of switching.

[Brief description of drawings]

1 is a system diagram of an engine with a supercharger according to a first embodiment of the present invention, FIG. 2 is a control flow chart of the apparatus of FIG. 1, and FIG. 3 is an engine speed according to the control flow of FIG. -Charging pressure characteristic diagram, FIG. 4 is a system diagram of an engine with a supercharger according to a second embodiment of the present invention, and FIG. 5 is a system diagram of an engine with a supercharger according to a third embodiment of the present invention. FIG. 6 is a schematic system diagram of a conventional engine with a supercharger, FIG. 7 is a system diagram around a turbocharger showing exhaust pulsation of the engine of FIG. 6, and FIG. 8 is an exhaust switching valve in a conventional device. Relationship between supercharging pressure and time with respect to the distance between the auxiliary turbocharger turbine and the turbocharger turbine. It is a relational diagram with the number. 1 ... Engine 2 ... Surge tank 3 ... Exhaust manifold 4 ... Throttle valve 5 ... Throttle opening sensor 6 ... Intercooler 7 ... Main turbocharger 7a ... Main turbocharger turbine 8 ... Sub turbocharger 8a …… Turbine of sub turbocharger 10 …… Intake bypass valve actuator 11 …… Intake switching valve actuator 13 …… Intake bypass passage 14 …… Intake passage (downstream of compressor) 15 …… Intake passage (upstream of compressor) 16 …… The actuator for the first exhaust switching valve 17a The first exhaust switching valve 17b The second exhaust switching valve 18 The intake switching valve 24 Air flow meter 25 The first three-way solenoid valve 26 Second three-way solenoid valve 27 …… Third three-way solenoid valve 28 …… Fourth three-way solenoid valve 29 …… Engine control computer 30 …… Intake pipe pressure sensor 31… The actuator 41 ...... chamber of the wastegate valve 32 ...... fifth three-way electromagnetic valve 33 ...... intake bypass valve 34 ...... second exhaust switching valve

Claims (1)

(57) [Scope of utility model registration request] 1. A main turbocharger and a sub-turbocharger provided in parallel with the engine body, and an intake and exhaust system of an engine connected to the sub-turbocharger. When both are fully opened, the sub-turbocharger is overloaded. An intake switching valve and an exhaust switching valve that perform the charging operation and stop the supercharging operation of the auxiliary turbocharger when both are fully closed;
In the engine with a supercharger, the exhaust switching valve is a first exhaust switching valve provided on the turbine downstream side of the auxiliary turbocharger and an exhaust system of the engine connected to the turbine of the auxiliary turbocharger. A second exhaust switching valve which is provided upstream of the first exhaust switching valve, is closed when the boost pressure is lower than a preset pressure, and is opened when the boost pressure is equal to or higher than the preset pressure. The engine with a supercharger.